While it is known that televisions and computer monitors utilize flat panels and digital techniques to improve dimensional size and display quality, more improvements, such as 3D digital comb filters and 3D digital noise reduction, are currently under development. Recently, research and development efforts were made to improve the external environment of the display apparatus by using illumination devices as a means to provide ambient light to the external environment, i.e. the environment surrounding the display apparatus, such as the nearby walls.
Ambient light provided by the illumination device to the external environment of a display apparatus can create a comfortable atmosphere for the viewers. The viewers not only can enjoy the images on the display apparatus but also the ambient environment generated by the ambient light from the illumination device.
The ambient light can work with the images shown on the display apparatus. For instance, when a video on a television shows a thunderstorm, a dark and lightning effect can be created by the illumination device. More specifically, when lightning is shown on the screen, a flash can be generated by the ambient light to produce the effect of lightning in conjunction with the schemes on the screen. Therefore, the ambient light may be dynamic depending upon the contents shown on the display apparatus.
Moreover, sound can also play a significant role in creating different viewing experiences. Ambient light generated by the illumination device can work with sounds to create different viewing experiences for the audience.
Another example that demonstrates the need for ambient light is when the screen is small and does not cover the entire wall in front of the viewers. Here, the viewers must concentrate and focus on the small display screen and their eyes need to adjust frequently between the brightness of the image on the display screen and the surrounding environment. The ambient lighting technique can reduce the difference in brightness between the display screen and the surrounding environment such that the stress on viewers' eyes is reduced.
U.S. Pat. No. 5,255,171, entitled “Colored Light Source Providing Intensification of Initial Source Illumination”, by L. Douglas Clark discloses an illuminating device utilizing light emitting diodes (“LED”) as light sources and a reflector with parabolic reflecting walls. This illuminating device comprises various LEDs positioned at the base of the reflector and a diffuser attached to the opposite end thereof. However, this prior art primarily focuses on a light concentrator for use with a color optical scanning device, such as a line scanning imaging system or an area scan imaging system.
A suitable light source for projecting ambient light is selected based on factors such as: the light transmittance, mixture of different color LEDs, response time of the LEDs, orientation of light projection and the reflectivity of light. Furthermore, one can also physically combine such ambient light sources with a display apparatus or an audio apparatus since audio-video (“AV”) apparatuses are widely available.
Most ambient light illumination devices that use LEDs as light source adopt a complex design. For instance, such device may comprise a housing, a substrate or printed circuit board (PCB), a soft layer, a reflection plate, an adhesive layer, a diffusion layer and an external shell. This multi-layer structure makes it difficult to design, manufacture, assembly or maintain the illumination device. For the utilization of the LEDs on the PCB, all the necessary components positioned above the LEDs need to be carefully designed and arranged. Such complex structure can be very costly. In addition, having many separated parts and layers are not desirable since each layer will need to satisfy the conditions of the LEDs used. This may affect the overall performance of the illumination device.
The components of the abovementioned illumination devices, in particular the reflection plate, are typically made of metal. However, metal components are subject to oxidation when placed in contact with humidity. Since the inside of the illumination device is not in vacuum, the use of metal is not desirable in the long run. This is particularly true for multi-layered structure since the spaces among the layers can increase contact surface to air and water, thus promoting the oxidation process. Moreover, structure with multiple layers is not preferred when the temperature can rise inside the illumination device. As the LEDs emit light, the internal temperature increases. The design of the illumination device must take into account the rising temperature so that each layer and the structure as a whole can withstand the heat.
In view of the above, it is desirable to provide an illumination device that can effectively provide ambient light and can be economically manufactured and maintained. The present invention provides an illumination device with a simplified structure that can facilitate the manufacturing process and can generate and reflect light effectively. The present invention also provides the technical solutions to the deficiencies of the prior illumination device.